To　find　the　effective　part　and　effective　components　of　Angelica　sinensis　in　Siwutang　which　can　produce　an　arteriolar　vasodilation　in　rabbit.　In　this　paper,　the　lipophilic　extract　of　Angelica　sinensis　was　obtained　by　supercritical　fluid　CO2　extraction.　The　effective　part　and　the　effective　component　in　it　were　separated　and　identified　by　using　systematic　chromatographic　methods　including　column　liquid　chromatography　(CLC),　high　performance　liquid　chromatography,　cell　membrane　chromatography　and　gas　chromatography-mass　spectrometry.　The　results　showed　that　the　effective　part　was　the　elute　of　hexane-ethyl　acetate　from　the　extract　separated　by　the　silica　CLC,　and　the　effective　components　in　the　part　were　ligustilide,　dimethyl　phthalate　and　diethyl　phthalate　respectively.